Details on the situation of two criniviruses of tomato in Italy and Portugal
At the request of the EPPO Secretariat, Italy and Portugal have kindly provided the following data on the present situation of two tomato criniviruses in their countries.
In Italy, both Tomato chlorosis crinivirus (ToCV- EPPO Alert List) and Tomato infectious chlorosis crinivirus (TICV - EPPO Alert List) occur. No specific evaluation of yield reduction has been made for the moment. It is felt that in Italy, Tomato yellow leaf curl begomovirus and Tomato spotted wilt tospovirus are causing more serious diseases. TICV was detected in Sardegna, Liguria, Lazio and Campania on a few samples. ToCV was detected in Sardegna, Sicilia and Puglia, again on a limited number of samples.
In Portugal, Tomato chlorosis crinivirus (ToCV) has been detected since 1999, in protected tomato crops in the Algarve region (south), where its two vectors Bemisia tabaci and Trialeurodes vaporariorum occur. ToCV has not been found in other regions. It was found in single or mixed infection with Tomato yellow leaf curl begomovirus. Symptoms are very similar to those described for Tomato infectious chlorosis crinivirus (EPPO Alert List) which does not occur in Portugal. Affected tomato plants show leaf yellowing, delayed ripening and produce less fruits, leading to a loss of fruit quality and commercial value. All tomato cultivars which are commonly cultivated in Algarve are susceptible to ToCV, and some new cultivars which were tolerant/resistant to Tomato yellow leaf curl begomovirus are highly susceptible to ToCV (disease incidence up to 100%). However, the economic impact of single infections of ToCV on crop losses has yet to be determined. Symptoms are often confused by the growers with physiological disorders or phytotoxicity damage. Surveys done only on the basis of visual symptoms are not reliable, and diagnostic methods (molecular assays) should be used. Two common weed species, Datura stramonium and Solanum nigrum, were identified as natural hosts of ToCV and, in addition, they are preferential hosts for the whitefly vectors. It is suspected that these weeds, and probably other wild species, might play an important role in the epidemiology of the disease, as plant reservoirs for the virus and its vectors between tomato-growing seasons. It is considered that the eradication of ToCV in Algarve is not feasible, as the vectors and natural plant reservoirs are present all year round.
Sources
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NPPO of Italy, 2002-05.
NPPO of Portugal, 2002-04.
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